Judge Boshier said it was crucial that police correctly recognised an incident as being family violence when they were called out.
"In some cases it will be obvious but in others that will not be so."
The statistics showed only that reported family violence may have levelled off or dropped slightly, he said.
"I think it premature to suggest that rates of family violence in New Zealand are dropping to any great extent.
"I fear that investment in elimination of family violence may need to compete strongly with other demands and I believe we need to be very vigilant on this front."
Judge Boshier warned the Government not to scrap stopping violence programmes, which are mandated when courts make protection orders.
In its "Reviewing the Family Court - a public consultation paper" released in September, the Government said it could be more efficient for other agencies to oversee the programmes.
Judge Boshier said a review of the programmes was needed, including what offenders should attend what programmes, and whether more support should be offered to victims.
"But I warn against the loss of mandatory programmes under the guise of suggesting some other Government agency will fill the void."